Development of cloud monitoring system at Simons Array

Simons Array is a ground-based experiment at the Atacama Desert in Chile that observes polarization anisotropies on cosmic microwave background with more than 20,000 detectors sensitive to 90, 150, 220, and 270 GHz band. It is necessary to monitor the tropospheric clouds, which Rayleigh scatter the thermal radiation of the ground and produce polarized noise. We have tested two types of cloud monitoring methods using an infrared (8-14 μm) camera and an all-sky visible-light camera. We present the data from the cloud monitors at the site and development of the cloud detection algorithm using machine learning techniques.